1. Field of the Invention
The invention relates to an air-leaning apparatus for room air, especially an electrostatic air-cleaning apparatus, having a housing, in which an inlet nozzle and an outlet nozzle for an air-current to be cleaned are provided, which is led to an air-cleaning unit provided in said housing, wherein said housing of said air-cleaning apparatus is column-like, wherein said air cleaning unit in the column-like housing is tube-like, wherein said column-like housing comprises an essentially air-tight outer sheath, and wherein said inlet nozzle for said air-current to be cleaned is provided in a first front face of said column-like housing.
2. Discussion of the Prior Art
Such an air-cleaning apparatus for room air is known from DE-OS 2 132 410. There the outlet nozzle is arranged in the outer sheath of the housing of the known air-cleaning apparatus. Such an arrangement brings forth in a disadvantageous manner that the course of flow of the air current passing through the known air-cleaning apparatus is not straight, so that, in an disadvantageous manner, turbulences occur in the course of flow, which express themselves in a noise level which is extremely disadvantageous for air-cleaning apparatus for room air.
A further disadvantage of the outlet nozzle provided in the outer sheath of the known air-cleaning apparatus is given by the fact that hereby the cleaned air leaving the known air-cleaning apparatus is not led away far enough from the air-cleaning apparatus. So, in a disadvantageous manner, a large part of the cleaned air is sucked in again by the inlet nozzle and is supplied to the air-cleaning unit of the known air-cleaning apparatus again.
A further disadvantage of the known air-cleaning apparatus is due to the inlet opening of the air-cleaning unit having a much smaller diameter than the inlet nozzle of the column-like housing, so that a diminuition of the current cross-section occurs in the known air-cleaning apparatus. This causes in an disadvantageous manner turbulences in the region in front of the air-cleaning unit, leading to a deterioration of the flow characteristic in the air-cleaning unit of the known air-cleaning apparatus and by this to a reduction of its cleaning power.
The different diameters of the inlet nozzle of the column-like housing and the inlet opening of the air-cleaning unit has further the disadvantage that a barrier element for the air current has to be provided in the known air-cleaning apparatus, which prevents a part of the air current entering through the inlet opening of the known air-cleaning apparatus from bypassing the air-cleaning unit. Such a barrier element is also unfavourable from a aerodynamically point of view, because it leads to further turbulences of the air current and by this to a reduction of the cleaning power and a rise in the noise development.
From the DE-OS 2 035 789, such an air-cleaning apparatus comprising an electrostatic separator equipment is known. The air to be cleaned is ionized in a gas ionizer in a high voltage field, so that the floating particles in the air put against a separating surface of a following separator having also a high voltage field. The known electrostatic separator is arranged in a box-like housing having a cylindrical cross section with a noticeable larger diameter than the gas ionizer arranged inside the apparatus.
This above described electrostatic separator equipment as well as all the other known air-cleaning apparatus are, due to their box-like housings, only capable of cleaning the lower air layers of a room, so that a cleaning of the upper air layers can be accomplished not at all or only very insufficiently.
The known air-cleaning apparatus are capable of cleaning only a small amount of air per hour. This is caused by the fact that the known air-cleaning apparatus used in living spaces, business premises or restaurants must be built relatively compact, because most of the customers regard it as disturbing, if, for example in their living room, a bulky box stood, which would be necessary with a known air-cleaning apparatus in order to accommodate the technical components necessary for achieving an adequate cleaning performance.
Due to the positioning of the known air-cleaning apparatus near to the floor, the employable power of a fan sucking in the air is relatively small, as otherwise the persons being in that room would be exposed to an unpleasant draft.
Because of the compact construction of the known air-cleaning apparatus due to the above-mentioned reasons, only very poor sound isolation means can be employed, which is therefore capable only to absorb a small amount of the operating noises of the known air-cleaning apparatus. This once again leads to only a limited performance of the known air-cleaning apparatus.
From DE-OS 35 28 591, there is known a column-like air conditioning device, the housing of which has an essentially air-tight outer sheath and is provided with an inlet and an outlet opening. The air conditioning device consists of a fan having on its pressure side an ion generator and an electric dust separator located on the feed side of the ion generator. The disadvantage of the known air conditioning device is that it only can be set-up in its horizontal direction, so that also with this device the afore-described disadvantages still occur.
From DE-OS 39 21 387, there is known a box-like air-cleaner having air inlet openings in its lateral surface. The air current being sucked in through one of these air inlets openings streams through an electric separating device using a corona discharge.
From JP 60-114361 in Patents Abstracts of Japan, sect. C, vol.9 (1985), no. 260 (C309), there is known an air-cleaning apparatus having air inlet and air outlet openings at both of its lateral surfaces, whereby the air current entering through the inlet opening passes through an electrostatic cleaning device.
From WO 8/103141, there is known an air-cleaning apparatus for treating the emission products of a wood burning stove. The requirements, which this air-cleaning apparatus has to fulfill in order to accomplish its function, are generally not compareable to those for an air-cleaning apparatus for room air, which is designed for an employment in living rooms. While the air-cleaning apparatus for room air has to have a low noise level, does not cause draught, and has to be built in an aesthetic way, these properties do not play any role for an air-cleaning apparatus used in an exhaust fume cleaning-system like the one known from the above-mentioned document. Furthermore, the known air-cleaning apparatus provides that the emission products produced by the combustion furnace are supplied to a vertically mounted air-cleaning unit by a passageway. In order to easily discharge the filtered, condensated emission products, the known air-cleaning apparatus has trays between the inlet nozzle of the air-cleaning apparatus and the end of the passageway having a smaller diameter as the passageway. Such trays are very disadvantageous in an aerodynamic aspect. Such a narrowing of the current path of the air current to be cleaned by the trays leads inevitabely to turbulences bringing forth a decreasing efficiency as well as to a noise development being not acceptable for air-cleaning apparatus for room air being used in living rooms.
The U.S. Pat. No. 3,623,295 describes an exhaust fume cleaning-system being preferably designed for use in automobiles. It comprises an air-cleaning unit being mounted in a tube. One end of the tube is linked to the muffler of a motor vehicle, so that the emission products escaping from the motor of the vehicle are already cooled in the muffler as well as reduced in respect to their pressure. Such a system is not suitable for the use as an air-cleaning apparatus for room air because it is not capable to fulfill the afore-described requirements for such air-cleaning apparatus for living rooms.